var getHTML = function ( url, callback ) {
    // Feature detection
    if ( !window.XMLHttpRequest ) return;

    var xhr = new XMLHttpRequest();

    xhr.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
            callback(this.response);
        }
    };

    // Get the HTML
    xhr.open( 'GET', url, true );
    xhr.responseType = 'json';
    xhr.send();
};

getHTML('https://en.wikipedia.org/w/api.php?action=query&prop=revisions&rvprop=content&format=json&titles=Tom_Clancy%27s_The_Division_2&rvsection=0&origin=*', function(jsonResponse) {
    var searchString = jsonResponse.query.pages['56786234'].revisions[0]['*'];
    document.querySelector("h1").innerHTML = searchString.split('| released = ')[1].split('{')[0];
});